In general, a commutator motor blower with a rotary motor incorporated therein is configured as described below with reference to FIG. 2. FIG. 2 is a partial side cross-sectional view illustrating the configuration of a commutator motor blower with a typical rotary motor incorporated therein.
As shown in FIG. 2, the commutator motor blower with the rotary motor incorporated therein includes motor section 6 and fan section 7. Motor section 6 has at least field magnet 16 with field winding 17, and armature 1 including commutator 8 and armature winding 9. Armature 1 is provided with shaft 10, and armature 1 is supported by shaft 10 pressed into bearings 11 provided in fan-side bracket 12 and commutator-side bracket 13 which constitute both ends of the motor. Brush holder 14 includes a metal with carbon brush 15 built therein, and held in commutator-side bracket 13.
Further, fan section 7 is provided with fan 18 for sucking air from intake 19 (upper side in FIG. 2) and blowing the air out to the outer periphery of fan 18. Then, the wind (air) blown out to the outer periphery of fan 18 is partially introduced into motor section 6 to cool down armature winding 9 of armature 1, etc.
Conventionally, the electric wire constituting field winding 17 of field magnet 16 or the armature winding of armature 1 in the rotary motor incorporated in the commutator motor blower structured as described above is firmly fixed with a coating material containing so-called varnish. This fixing suppresses vibrations and sounds caused by the movement of the electric wire during the rotation of the rotary motor. In addition, the fixing prevents the decrease in insulation property caused by degradation of the insulation film coating the electric wire, due to frictions between electric wires. Therefore, the varnish (coating material) has been important, which is applied for adequately firm fixation of electric wires in a slot to each other, and of the electric wires to the slot.
On the other hand, the rotary motor undergoes a decrease in efficiency due to, for example, iron loss, copper loss, mechanical losses such as bearing loss and brush wear loss, and windage loss. Therefore, in order to drive the rotary motor with high efficiency, it is important to reduce these losses. In particular, rotary motors for use in, for example, blower motors for vacuum cleaners are currently driven by high-speed rotations at 40000 rotations/min or more. Therefore, in the rotary motors rotating at high speed, windage losses are dominant, which lead to a decrease in efficiency on the order of approximately 10%. More specifically, the rotary motors rotating at high speed can significantly improve the efficiency through the reduction of windage losses.
However, in general, varnish is applied to coil ends of armature 1 including armature winding 9, only to such an extent that electric wirings are firmly fixed to each other. Therefore, there is a problem that at the coil ends of armature 1, irregularity formed by aggregation of electric wires generates turbulent flows to increase windage losses.
In order to avoid the problem, motors for the disclosure of methods for reducing windage losses due to irregularity are described in, for example, Patent Documents 1 to 4 conventionally.
Patent Document 1 discloses, for an AC commutator motor, a technique of applying electrically insulating coating materials that differ in viscosity twice or more, more than once, to increase the thickness of the coating materials, and smooth the irregularity caused by aggregation of electric wires at coil ends. Specifically, first, the lower-viscosity coating material is applied to electric wires at the coil ends to cause the coating material to penetrate between the electric wires, and firmly fix electric wires in a slot to each other and the electric wires to the slot. Thereafter, the higher-viscosity coating material is applied onto the coil ends with the lower-viscosity coating material applied thereon. Thus, it is concluded that the thick application of the coating materials onto the coil ends can smooth the irregularity.
In addition, Patent Document 2 discloses, for a motor blower, a technique of planarizing irregularity of coil ends with an insulating mold material, and also discloses integrally forming a rotational balance adjustable member.
In addition, Patent Document 3 discloses, for a commutator motor blower, a technique of covering the outer periphery of a fan-side winding wire of an armature with a windage-loss reducing cover including an insulating material.
In addition, Patent Document 4 discloses, for a motor, a technique of smoothly applying an electrically insulating resin onto coil ends by providing the outer periphery of the rotary shaft of the coil ends with a resin movement restricting member for restricting the flow of the electrically insulating resin to be applied.
However, Patent Document 1 for the AC commutator motor discloses the application of the two or more coating materials which differ in viscosity, but fails to disclose any specific composition or viscosity of the coating materials. In general, the viscosity of a coating material significantly varies depending on temperatures. Therefore, in the disclosure of Patent Document 1, it is not clear which temperature is appropriate for the viscosities of the coating materials, or how large difference in viscosity is effective. For example, even when the higher-viscosity coating material is used at room temperature, the viscosity of the coating material may be decreased in some cases while heating to the curing temperature of the coating material is performed after the application, thereby failing to achieve the effect of smoothing the irregularity.
In addition, when a coating material simply with a high viscosity is thickly applied to the coil ends, the coating material has a crack generated by curing and shrinkage after the application. Moreover, there is a problem in terms of reliability, such as the coating material also with a crack generated, or peeling caused during the high-speed rotation of the AC commutator motor, and depending on changes in temperature.
In addition, the motor blower in Patent Document 2 requires a structurally complex mold, because the insulating mold material is integrally formed which also serves as the rotational balance adjustable member. In addition, the motor blower has problems such as decreased insulation performance for the electric wires, or disconnection, due to the pressure for the forming of the insulating mold material, etc. Furthermore, there is a need to use a high-density insulating mold material for also use as the rotational balance adjustable member. Therefore, there is a problem that the weight the armature itself is significantly increased to increase the bearing loss.
In addition, the commutator motor blower in Patent Document 3 has a problem that an air layer between the windage-loss reducing cover and the coil end increases the temperature of the fan-side winding wire to increase copper loss. In addition, in order to use the commutator motor blower as a motor for vacuum cleaner, a thick and large windage-loss reducing cover is required which withstands the centrifugal force of the armature rotating at high speed. Therefore, the motor has difficulty with practical use.
In addition, the motor in Patent Document 4, which is provided with the resin movement restricting member, allows the coating material to be applied thickly to some extent, even when a low-viscosity varnish is used. However, a large resin movement restricting member is required in order to apply adequate varnish in the gaps between electric wires and in a slot, and apply varnish that can smooth irregularity caused by electric wires at the coil ends. In addition, there is a problem that the windage loss due to irregularity of the electric wires on the commutator side of the armature is not able to be suppressed, because the resin restricting member is not able to be placed at the commutator-side coil end of the armature.